1. Field of the Invention
The present invention relates generally to the treatment of anatomical tissue of the head and/or neck with high intensity focused ultrasound energy and, more particularly, to skin rejuvenation by thermal stimulation using high intensity focused ultrasound.
2. Brief Description of the Related Art
When high intensity ultrasound energy is applied to anatomical tissue, significant physiological effects may be produced in the anatomical tissue resulting from thermal and/or mechanical changes or effects in the tissue. Thermal effects include heating of the anatomical tissue; and, when the tissue is heated to a sufficiently high temperature, tissue damage such as coagulative necrosis is produced. In order to produce thermal effects in anatomical tissue, ultrasound emitting members such as transducers have been used to emit ultrasound energy which is applied to anatomical tissue by positioning the ultrasound emitting members adjacent or in contact with the tissue or by coupling the ultrasound emitting members to the tissue via an acoustic coupling medium. By focusing the ultrasound energy at one or more specific focusing zones within the tissue, thermal effects can be confined to a defined location, region, volume or area, and such location, region, volume or area can be remote from the ultrasound emitting member.
With the use of high intensity focused ultrasound (HIFU), one or more focusing zones at or within a designated target location, region, volume or area within a larger mass, body or area of anatomical tissue can be subjected to high intensity ultrasound energy while tissue surrounding the target area is subjected to much lower intensity ultrasound energy. In this manner, tissue in the target area can be heated to a sufficiently high temperature so as to cause a desired thermal effect such as tissue damage, ablation, coagulation, denaturation, destruction or necrosis while tissue surrounding the target area is not heated to damaging temperatures and, therefore, is preserved. Heating of tissue in a target location, volume, region or area to an ablative temperature creates an ablative lesion in the tissue in the target location, volume, region or area that is desirable in the treatment of various medical conditions, disorders or diseases. For example, the lesion may remain as tissue having altered characteristics or may be naturally degraded and absorbed by the patient""s body and thusly eliminated such that the remaining body, mass or area of tissue is of smaller volume or size due to the absence of the ablated tissue.
The use of high intensity focused ultrasound to eliminate tissue or to alter the characteristics of tissue in a target location, volume, region or area within a larger mass, body or area of anatomical tissue presents many advantages including minimization of trauma and pain for the patient, elimination of the need for a surgical incision, stitches and exposure of internal tissue, avoidance of damage to tissue other than that which is to be treated, altered or removed, lack of a harmful cumulative effect from the ultrasound energy on the surrounding non-target tissue, reduction in treatment costs, elimination of the need in many cases for general anesthesia, reduction of the risk of infection and other complications, avoidance of blood loss, and the ability for high intensity focused ultrasound procedures to be performed in non-hospital sites and/or on an out-patient basis.
Various devices and/or methods for treating anatomical tissue with ultrasound have been proposed as represented by U.S. Pat. No. Re. 33,590 to Dory, U.S. Pat. No. 3,990,452 to Murry et al, U.S. Pat. No. 4,658,828 to Dory, U.S. Pat. No. 4,807,633 to Fry, U.S. Pat. No. 4,858,613 to Fry et al, U.S. Pat. No. 4,951,653 to Fry et al, U.S. Pat. No. 4,955,365 to Fry et al, U.S. Pat. No. 5,033,456 to Pell et al, U.S. Pat. No. 5,036,855 to Fry et al, U.S. Pat. No. 5,054,470 to Fry et al, U.S. Pat. No. 5,065,761 to Pell, U.S. Pat. No. 5,080,101 to Dory, U.S. Pat. No. 5,080,102 to Dory, U.S. Pat. No. 5,117,832 to Sanghvi et al, U.S. Pat. No. 5,134,988 to Pell et al, U.S. Pat. No. 5,143,074 to Dory, U.S. Pat. No. 5,150,711 to Dory, No. 5,150,712 to Dory, U.S. Pat. No. 5,158,070 to Dory, U.S. Pat. No. 5,222,501 to Ideker et al, U.S. Pat. No. 5,267,954 to Nita, U.S. Pat. No. 5,269,291 to Carter, U.S. Pat. No. 5,269,297 to Weng et al, U.S. Pat. No. 5,295,484 to Marcus et al, U.S. Pat. No. 5,304,115 to Pflueger et al, U.S. Pat. No. 5,312,328 to Nita et al, U.S. Pat. No. 5,318,014 to Carter, U.S. Pat. No. 5,342,292 to Nita et al, U.S. Pat. No. 5,354,258 to Dory, U.S. Pat. No. 5,380,274 to Nita, U.S. Pat. No. 5,391,197 to Burdette et al, U.S. Pat. No. 5,397,301 to Pflueger et al, U.S. Pat. No. 5,409,002 to Pell, U.S. Pat. No. 5,417,672 to Nita et al, U.S. Pat. No. 5,431,621 to Dory, U.S. Pat. No. 5,431,663 to Carter, U.S. Pat. No. 5,447,509 to Mills et al, U.S. Pat. No. 5,474,530 to Passafaro et al, U.S. Pat. No. 5,492,126 to Hennige et al, U.S. Pat. No. 5,501,655 to Rolt et al, U.S. Pat. No. 5,520,188 to Hennige et al, U.S. Pat. No. 5,542,917 to Nita et al, U.S. Pat. No. 5,620,479 to Diederich, U.S. Pat. No. 5,676,692 to Sanghvi et al, U.S. Pat. No. 5,728,094 to Edwards, U.S. Pat. No. 5,730,719 to Edwards, U.S. Pat. No. 5,733,315 to Burdette et al, U.S. Pat. No. 5,735,280 to Sherman et al, U.S. Pat. No. 5,738,114 to Edwards, U.S. Pat. No. 5,746,224 to Edwards, U.S. Pat. No. 5,762,066 to Law et al, U.S. Pat. No. 5,800,379 to Edwards, U.S. Pat. No. 5,800,429 to Edwards, U.S. Pat. No. 5,800,482 to Pomeranz et al, U.S. Pat. No. 5,807,308 to Edwards, U.S. Pat. No. 5,817,049 to Edwards, U.S. Pat. No. 5,823,197 to Edwards, U.S. Pat. No. 5,827,277 to Edwards, U.S. Pat. No. 5,843,077 to Edwards, U.S. Pat. No. 5,871, 524 to Knowlton, U.S. Pat. No. 5,873,845 to Cline et al, U.S. Pat. No. 5,873,902 to Sanghvi et al, U.S. Pat. No. 5,879,349 to Edwards, U.S. Pat. No. 5,882,302 to Driscoll, Jr. et al, U.S. Pat. No. 5,895,356 to Andrus et al, U.S. Pat. No. 5,928,169 to Schxc3xa4tzle et al and U.S. Pat. No. 5,938,608 to Bieger et al.
In particular, the use of high intensity focused ultrasound to thermally damage, ablate, coagulate, denature, cauterize, necrotize or destroy a target volume of tissue is exemplified by U.S. Pat. No. Re. 33,590 to Dory, U.S. Pat. No. 4,658,828 to Dory, U.S. Pat. No. 4,807,633 to Fry, U.S. Pat. No. 4,858,613 to Fry et al, U.S. Pat. No. 4,951,653 to Fry et al, U.S. Pat. No. 4,955,365 to Fry et al, U.S. Pat. No. 5,036,855 to Fry et al, U.S. Pat. No. 5,054,470 to Fry et al, U.S. Pat. No. 5,080,101 to Dory, U.S. Pat. No. 5,080,102 to Dory, U.S. Pat. No. 5,117,832 to Sanghvi et al, U.S. Pat. No. 5,143,074 to Dory, U.S. Pat. No. 5,150,711 to Dory, U.S. Pat. No. 5,150,712 to Dory, U.S. Pat. No. 5,295,484 to Marcus et al, U.S. Pat. No. 5,354,258 to Dory, U.S. Pat. No. 5,391,197 to Burdette et al, U.S. Pat. No. 5,431,621 to Dory, U.S. Pat. No. 5,492,126 to Hennige et al, U.S. Pat. No. 5,501,655 to Rolt et al, U.S. Pat. No. 5,520,188 to Hennige et al, U.S. Pat. No. 5,676,692 to Sanghvi et al, U.S. Pat. No. 5,733,315 to Burdette et al, U.S. Pat. No. 5,762,066 to Law et al, U.S. Pat. No. 5,871,524 to Knowlton, U.S. Pat. No. 5,873,845 to Cline et al, U.S. Pat. No. 5,873,902 to Sanghvi et al, U.S. Pat. No. 5,882,302 to Driscoll, Jr. et al, U.S. Pat. No. 5,895,356 to Andrus et al, U.S. Pat. No. 5,928,169 to Schxc3xa4tzle et al and U.S. Pat. No. 5,938,608 to Bieger et al.
The skin is the largest organ of the body and is highly vulnerable to deterioration due to natural aging and/or exposure to environmental conditions such as sun, wind, heat and cold. The skin includes two primary layers, i.e. the epidermis and the dermis. The epidermis is the outermost layer of the skin and presents a barrier to deter the entry of UV radiation, germs, heat, cold, dirt and gases while deterring the egress of water, blood, minerals, vitamins, hormones and protein. The epidermis is composed of a plurality of sub-layers including several layers of stratified epithelial tissue. The basilar layer of the epidermis includes melanocytes and other epithelial cells. Melanin is produced by the melanocytes and serves to protect the skin from harmful effects of ultraviolet radiation. Skin cells are continuously moving from the lower layers to the upper layers of the epidermis and are sloughed off after they reach the skin surface. The dermis is comprised of dense, irregular connective tissue and contains blood vessels, sweat glands, sebaceous glands, nerves, collagen and elastin. Collagen contributes to the firmness of the skin, and elastin imparts flexibility and durability to the skin. The potential outcome of increased collagen levels in facial skin is a reduction of wrinkles with enhanced skin resilience and a more youthful appearance.
There is a great demand for methods or procedures to reduce the effects of aging and/or environmental exposure in skin and, in particular, facial skin. Conventional techniques for removing facial wrinkles include cosmetic or plastic surgery, one technique being commonly known as xe2x80x9cskin resurfacingxe2x80x9d. Cosmetic surgery has numerous drawbacks including invasiveness, trauma, scarring, pain, significant recovery times and high financial cost. Conventional, non-surgical techniques for removing facial wrinkles involve destruction of the epidermis and/or dermis by laser energy used to vaporize the tissue, chemical burns or peels, physical debridement using drills and blasting the skin with a pressurized stream of beads. Such non-surgical techniques typically destroy the epidermis, resulting in temporary and possibly permanent impairment of the skin. For example, patients may be left with various pigmentation problems including blotchiness, a predominantly white complexion and/or the inability to tan.
U.S. Pat. No. 5,743,904 to Edwards discloses RF ablation of body structures, including fatty tissues in the cheeks, jaw and near the eyes, via electrodes inserted in the tissue. U.S. Pat. No. 5,871,524 to Knowlton discloses the use of RF electrodes and an electrolytic solution to create a reverse thermal gradient in the skin to effect partial denaturation and shrinkage of collagen resulting in tightening of the skin. Ultrasound is alluded to as a possible source of radiant energy to create the reverse thermal gradient. The stimulation of collagen growth by delivery of energy into the superficial layers of the dermis has also been recognized. Lasers having wavelengths that penetrate the epidermis without damage thereto and stimulate the dermis to create collagen are being developed and marketed.
It has not been previously recognized to thermally stimulate collagen growth by delivery of focused ultrasound energy into superficial layers of the dermis, while avoiding damage to the epidermis, in a minimally invasive, non-traumatic procedure not requiring physical penetration or wounding of the skin and while confining thermal stimulation to a specific target area or areas within the skin.
Accordingly, it is a primary object of the present invention to overcome the various disadvantages of prior methods of skin rejuvenation.
It is also an object of the present invention to effect skin rejuvenation by using high intensity focused ultrasound to stimulate collagen growth.
Another object of the present invention is to utilize high intensity focused ultrasound to effect wrinkle reduction by increasing collagen levels in skin.
It is also an object of the present invention to use high intensity focused ultrasound to thermally stimulate collagen growth in skin without impairing the epidermis.
The present invention also has as an object to use high intensity focused ultrasound to thermally stimulate superficial layers of the dermis to increase collagen growth without damaging the epidermis.
Still a further object of the present invention is to focus ultrasound energy within the skin to form an internal ablated tissue area beginning a predetermined distance beneath an external surface of the skin in order to stimulate collagen production.
The present invention also has as an object to focus ultrasound energy, emitted by an ultrasound emitting member, within the skin to form an internal ablated tissue area beginning a predetermined distance from an active face of the ultrasound emitting member in order to stimulate collagen production.
It is another object of the present invention to use high intensity focused ultrasound to form an ablated tissue area in the skin to a predetermined depth so that deep layers of the skin are not damaged.
An additional object of the present invention is to focus ultrasound energy within the skin to form an ablated tissue area in the superficial layer of the dermis but not the deep layer of the dermis.
Some of the advantages of the present invention are that varying intensity levels of ultrasound energy can be delivered to the skin for varying periods of time depending on desired ablative effect, the duration of ultrasound energy delivery or application to the skin needed to accomplish a desired stimulation may be relatively brief depending on desired size for the lesions of the ablated tissue area and/or desired thermal effect on the tissue, the transducer or other member used to emit the ultrasound energy may be stationary or may be movable in order to scan a target area with focused ultrasound, a plurality of individual ablated tissue areas can be formed in the skin with the ablated tissue areas being separate and discontinuous or being contacting, abutting, contiguous or overlapping to form a single continuous ablated tissue area of desired size and/or shape, the ultrasound emitting member can remain stationary or can be moved along the skin to scan a target area with focused ultrasound, the transducer or other member may be designed with a focusing configuration designed to ensure that the lesions of the ablated tissue area have a desired cross-sectional size, begin a desired depth within the skin and have a desired depth, the superficial dermis is thermally damaged to stimulate collagen growth with minimal trauma and pain for the patient, the transducer or other member is positioned externally adjacent or in contact with an external surface of the skin or is acoustically coupled with the skin to form an internal ablated tissue area without damaging the external skin surface and, in particular, the epidermis, no external wound is presented since the epidermis is preserved, and an ablated tissue area of definitive size can be repeatedly and consistently produced.
These and other objects, advantages and benefits are realized with the present invention as generally characterized in a method of skin rejuvenation or wrinkle reduction by thermal stimulation using high intensity focused ultrasound wherein an ultrasound emitting member is positioned adjacent an external surface of the skin, and ultrasound energy is emitted from the ultrasound emitting member into the tissue of the skin. The ultrasound energy is focused within the skin at a plurality of focusing zones disposed beneath the external skin surface and contained in a target area coincident with or containing the superficial dermis. The focusing zones are spaced from one another and, due to focusing of the ultrasound energy at the focusing zones, the ultrasound energy is of higher or greater intensity in the tissue at the focusing zones than in the tissue surrounding the focusing zones. The tissue of the skin is heated at the focusing zones by the focused ultrasound energy, thereby forming an ablated tissue area below the external skin surface containing unablated skin tissue and a plurality of lesions at the focusing zones, respectively, at which the tissue of the skin is ablated. Once an ablated tissue area of desired extent has been obtained in the skin, the ultrasound emitting member is removed. In reaction to the lesions, natural production of collagen in the dermis is stimulated. Collagen levels in the skin are thusly increased, resulting in a reduction of wrinkles and enhanced skin resilience for a more youthful appearance.
The ultrasound emitting member has a focusing configuration causing the ultrasound energy to be focused a predetermined distance from an active face of the ultrasound emitting member and, therefore, from the external surface of the skin, so that the epidermis is undamaged and preserved. Also, the focusing configuration results in formation of lesions of predetermined or known depth in accordance with the length of the focusing zones, the selected ultrasound energy intensities and the selected duration times for ultrasound energy delivery. The lesion depths are selected so that the lesions do not extend deeper than desired in the skin, thereby avoiding damage to the deep layer of the dermis. The plurality of lesions may be non-contacting, with each lesion surrounded by unablated skin tissue. One or more of the plurality of lesions may contact another one of the plurality of lesions. The cross-sectional size of the lesions and the location and arrangement of the focusing zones in the skin result in formation of a specific size ablated tissue area having a specific cross-sectional configuration. A single, discrete ablated tissue area or a plurality of single, discrete ablated tissue areas can be formed in the skin in a single procedure or treatment performed at one time or in multiple procedures or treatments performed at different times. Where a plurality of ablated tissue areas are formed, the ablated tissue areas can be contiguous, contacting, overlapping or in abutment with one another so that the ablated tissue areas together form or create a single ablated tissue area of larger cross-sectional size and/or of a desired cross-sectional configuration.
Other objects and advantages of the present invention will become apparent from the following description of the preferred embodiments taken in conjunction with the accompanying drawings, wherein like parts in each of the several figures are identified by the same reference characters.